JPH0258802A - Platinum resistance thermometer and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a platinum thermistor made of a thin platinum film and having a high resistance temperature coefficient by forming the platinum film on an insulating film of a different kind of material formed on the surface of a substrate and constituting the insulating film of zirconium oxide. CONSTITUTION:After a TiO2 film 12 is formed on the surface of an Al2O3 substrate 11 by injecting O2 gas after exhausting air by sputtering, a platinum film 13 having a thickness of 0.4-1.6mum is formed by a vacuum deposition method, sputtering method, etc. After patterning the platinum film 13 to a desired form, the film 13 is subjected to heat-treatment at 900-950 deg.C and resistance value adjustment by trimming. Then the base plate 13 is divided into individual pieces and lead wires 14 are connected to each piece. Therefore, a platinum film which is thinner in thickness and higher in stable resistance coefficient than the conventional example can be obtained and the using quantity of highly expensive platinum can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a platinum resistance temperature sensor whose main component is platinum, which is used as a temperature sensor, and a method for manufacturing the same.

Conventional Technology Platinum has long been used as a temperature sensor material because it is chemically stable and easily obtainable with high purity and gloss, and its electrical resistance is highly dependent on temperature. Platinum wire, which is punishable by up to 100%, is wrapped spirally around an insulator such as mica and inserted into a protective tube.It is widely used as a resistance probe, and the standard is specified in JISC-1604. It is being Although this type of platinum resistor has high precision, ■ it has weak mechanical strength.

■ Due to its structure, it takes time to manufacture.

■ Large shape.

■ It is expensive.

It had many drawbacks.

Temperature measuring resistors using thick or thin film platinum that eliminate these drawbacks have been actively developed in recent years, and some are commercially available. However, because thick-film platinum resistors are made using NuClean printing technology, it is difficult to create fine patterns of 100 μm or less, there is considerable variation in performance, and it is difficult to achieve high TCR characteristics due to the material composition. It has the following drawbacks. On the other hand, thin film platinum resistance thermometers.

■ The pattern is fine, easy to form into a compound, miniaturization can be achieved, and high sensitivity can be achieved by increasing the length and resistance.

■ Strong bandit-like strength.

■ Variations can be reduced through wafer processing, making it suitable for mass production and lower prices.

It has the following advantages.

As a method for manufacturing a resistance temperature sensor using thin film platinum.

First, a platinum film with a thickness of several thousand angstroms is formed on a Ziroku substrate by vacuum evaporation, sputtering, etc.
This platinum thin plate is made into a fine pattern using a wet etching method, a nupatta etching method, etc.
-V is best to perform high temperature heat treatment at 0'C. after that,
Adjust the resistance value by trimming, make a chip, and attach lead wires to make a resistance temperature detector.

However, the temperature coefficient of the platinum thin film produced by such a method exhibits a linearity, which is considerably smaller than the resistance temperature coefficient of the bulk. Possible reasons for this are as follows.

That is, among the characteristics of such a thin film as a material, those that have a large influence on its physical properties include size effects and structural defects.

The size effect is due to inelastic scattering of electrons in a thin film.
This is an effect that appears in the so-called electron transport phenomenon caused by a decrease in the effective mean free path of electrons. The effect becomes particularly noticeable when the film thickness is equal to or less than the mean free path of electrons.

In addition, the thin film formation process often involves rapid agglomeration from a gas layer to a solid layer in a space where gas molecules and ions, more or less unrelated to the thin film substance, exist. Vacancies, interstitial atoms.

Various structural defects inherent in crystals such as lattice defects, grain boundaries, etc. are introduced, and foreign atoms and molecules are mixed in as impurities, causing electron scattering.

Due to these effects, the specific resistance of the thin film becomes larger than that of the bulk, and therefore the temperature coefficient of resistance of the platinum thin film becomes lower than that of the bulk.

This causes a decrease in the sensitivity of the thin film platinum as an antibody.

In order to improve this, in the manufacturing method of platinum resistance temperature detectors, heat treatment is performed as described above, but the thickness of the produced platinum film is 1.
In the case of .mu.m or less, if the heat treatment temperature exceeds 1100.degree. C., the platinum film aggregates during the heat treatment to form an island-like non-uniform film, and the characteristics as a resistance temperature detector cannot be obtained.

Therefore, in order to stably obtain a high temperature coefficient of resistance, the thickness of the platinum film must be 1 μm or more, and it has not been industrially satisfactory to produce a thick layer of semi-solid platinum.

Problems to be Solved by the Invention It is an object of the present invention to eliminate the drawbacks of the above-mentioned prior art and to provide a platinum resistance thermometer having a thin platinum film and a high temperature coefficient of resistance.

Means for Solving the Problems The present inventors investigated various types and structures of substrates for producing platinum, and as a result, formed a VcT102 layer on the surface of the substrate,
It was discovered that the platinum film formed on the surface can have a high temperature coefficient of resistance with a thin film thickness compared to other substrate materials.

Effect Table 1 shows the results of comparing the crystallinity after heat treatment of the platinum film formed on the TiO2 layer formed on the base according to the present invention and the platinum film formed directly on the substrate using X-ray diffraction method. This is what is shown.

As shown in Table 1, the platinum film of the present invention is (111)
It can be seen that the plane D peak intensity is strong and the half value 11@ is small, both of which indicate high orientation. As described above, according to the present invention, as a result of the heat treatment increasing the crystallinity of the platinum film, TC
The R characteristics are improved.

Table 1 Results of analysis of platinum thin film by X-ray diffraction method (after heat treatment) Example The present invention will be specifically described below with reference to one drawing.

(Example-1) Figure 1 is a cross-sectional view of a platinum resistance temperature detector showing the first example of the present invention, and Figures 2c&) to (c) show the manufacture of the resistance temperature detector shown in Figure 1. FIG. 3 is a cross-sectional view at a stage.

Mu120. Base F! i, 11 by sputtering method (after exhausting to IX 10-6 (Torr), 6X
Inject 02 gas to 10-' (Torr) and increase to 400 (Torr).
After the Tie2 film 12 of about 1 μm was completely blown out with the power of W) (
2L), a platinum film 13 having a thickness of 04 to 1.6 μm is formed on the TiO□ film 12 by vacuum evaporation, sputtering, or the like (FIG. 2B).

After patterning the platinum film 13 into a desired shape (FIG. 2C)
), heat treated at 9oO to 950'C, adjusted the resistance value by trimming, and then divided into pieces.

Connect the lead wire 14.

(Example 2) FIG. 3 is a sectional view of a platinum resistance temperature detector showing a second example of the present invention.

As in Example-1, the surface of the Mu4203 substrate 11 was coated with (I x 10-6 (Torr)
) After exhausting, 0□ gas was injected to 6×1O-3 (Torr).

After generating a TiO□ film 12 of about 1 μm with a power of 400 (W), a platinum film 13 of 0.4 to 1.6 μm was formed on the TiO2 film 12 by vacuum evaporation, sputtering, etc. Thereafter, the platinum film 13 is patterned together with the TiO2 film 12 into a desired shape, heat treated at 900 to 960 DEG C., the resistance value is adjusted by trimming, the film is divided into pieces, and the lead wires 14 are connected.

(Example 3) FIG. 4 is a sectional view of a platinum resistance temperature detector showing a third example of the present invention.

The reaction chamber containing the titanium (Ti) substrate 16 is
After exhausting to X 10'''' (Torr), 4 X 1O-
02 was injected to 2 (Torr) and heated to 30°C.
After applying a DC voltage of 1.5 KV to the i-substrate 15 and forming a TiO□ film with a thickness of about 1 μm on the surface by ion oxidation.

T1 is applied to the surface by vacuum evaporation, sputtering, etc.
A platinum film 13 of 0.4 to 1.6 μm is formed on the substrate 15, and after patterning the platinum film 13 together with the TiO□ layer into a desired shape, heat treatment is performed at 9oO to 5eso'c, and the resistance value is adjusted by trimming. Divide into 1 piece and connect lead wire 14
Connect.

(Example 4) FIG. 5 is a sectional view of a platinum resistance temperature detector showing a fourth example of the present invention.

A platinum film 13 of 0.4 to 1.6 μm is formed on the surface of the titania (T102) substrate 16 by vacuum evaporation, sputtering, etc. on the surface of the TiO2 substrate 16, and then the platinum film 13 is patterned into a desired shape. death.

Heat treatment is performed at 900 to 950° C., and after adjusting the resistance value by trimming, it is divided into pieces, and lead wires 14 are connected.

(Comparative Example) FIG. 6 is a sectional view of a platinum resistance temperature detector showing a comparative example of the present invention.

After forming a platinum film 13 of 0.4 to 1.6/Am on the surface of the substrate 11 by vacuum evaporation, sputtering, etc., and patterning the platinum film 13 into a desired shape, 900 After heat treatment at ~960°C and adjusting the resistance by trimming, divide it into individual pieces and connect the lead wire 14.
Connect.

A current was passed through both ends of the platinum resistance thermometer.

The results of measuring the temperature coefficient of resistance (TCR) by measuring the change in resistance value between temperatures of o'C to 100C.

As shown in Table 2, the platinum resistance temperature detector according to the present invention is T
Higher values can be obtained compared to conventional products that do not use an iO2 layer.

Table-2 Relationship between the substrate material of the present invention and TICR characteristics (platinum film thickness 0.4μ) Also, these Examples-1, 2, 3, 4,
When examining the relationship between the platinum film thickness and the TCR for the platinum resistance thermometer in the comparative example, the relationship between the platinum film thickness and the TCR is as shown in FIG. 7.According to the present invention, a high TCR can be obtained even with a thin platinum film.

Effects of the Invention As described above, according to the present invention, the platinum thin film can stably obtain a high temperature coefficient of resistance in a thinner film than before, reduce the amount of platinum used, which has a high unit cost, and achieve high sensitivity. This makes it possible to provide a thin film platinum resistance thermometer at a low cost.

Another effect of the present invention is that the base material of the substrate can be freely selected, making it possible to control the thermal characteristics of the substrate such as heat capacity and specific heat, thereby improving thermal responsiveness, which is the second characteristic required of a resistance temperature detector. Improvements can be easily made, and it becomes possible to provide high-performance resistance temperature detectors at low cost. As an example of the effect of the present invention, the effect of forming a TiO
203) The explanation was given using an example of a substrate on which a TlO2 layer was formed, but it is also possible to
．． A similar effect can be obtained even in the case of Ti, etc.).

Furthermore, the method for forming the TiO□ layer and the method for producing the platinum film are not limited to the embodiments of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a platinum resistance temperature detector according to a first embodiment of the present invention, FIG. 2 aNC is a sectional view of the platinum resistance temperature detector of FIG. 1 at a manufacturing stage, and FIG. FIG. 4 is a sectional view of a platinum resistance temperature detector according to a third embodiment of the present invention, and FIG. 6 is a sectional view of a platinum resistance temperature detector according to a fourth embodiment of the present invention. FIG. 6 is a cross-sectional view of a platinum resistance temperature sensor showing a comparative example of the present invention.
FIG. 1 is a characteristic diagram showing the relationship between the temperature coefficient of resistance (TCR) and the platinum film thickness of platinum resistance temperature sensors according to examples of the present invention and comparative examples. 11...Mu C203 substrate, 12...Ti
O□ film, 13...Platinum film, 15...Ti
Substrate, 16...TiO□ substrate. Name of agent: Patent attorney Shigetaka Awano and 1 other person1
Figure 3 Figure 4 Figure 2

Claims (3)

[Claims] (1) A different type of insulating layer is formed on the surface of the substrate, a platinum film is formed on the insulating layer, and the insulating layer is made of titanium oxide (T).
A platinum resistance thermometer characterized by comprising iO_2). (2) The platinum resistance temperature detector according to claim 1, wherein the substrate is made of titanium oxide (TiO_2). (3) A method for manufacturing a platinum resistance thermometer, characterized in that a titanium oxide (TiO_2) layer and a platinum film are sequentially formed on a substrate, and then the platinum film and the TiO_2 layer are patterned into the same shape.